Third generation code division multiple access (CDMA) mobile systems, such as Universal Mobile Telecommunication System (UMTS) Third Generation Partnership Program (3GPP) wideband code division multiple access (W-CDMA), use searcher thresholds to detect propagation paths while ensuring a constant probability of false alarm.
One conventional system for ensuring a constant probability of false alarm involves minimizing automatic gain control (AGC) jittering using highly accurate analog components. A disadvantage to this approach is the increased system cost due to the high cost of highly accurate analog components.
Another conventional system involves adding additional digital hardware for measuring the total of the received-signal power plus the interference power, after analog-to-digital (A/D) conversion, and feeding back the measured total-received-signal-plus-interference power to the AGC or use the measured value directly to normalize the power measurements. A disadvantage of this approach is the need for additional hardware and its attendant expense.
Both of these conventional systems will only allow normalization based on a combined measurement of both signal and interference power. However, in order to ensure a constant probability of false alarm, the normalization should ideally happen based only on the interference power.